Multi-Piston Pump

ABSTRACT

The present invention relates to a multi-piston pump comprising a housing, a first pump unit having a plurality of piston pumps for the pressure supply of a first pressure circuit, a second pump unit having a plurality of piston pumps for the pressure supply of a second pressure circuit, a drive and an eccentric unit having a first eccentric and a second eccentric, wherein the first and the second eccentrics drive the plurality of piston pumps, and wherein the first and second pump units comprise in each case at least one piston pump which can be driven by the first eccentric and one piston pump which can be driven by the second eccentric. In that in each case, one piston pump which is driven by the first eccentric is arranged parallel to a piston pump which is driven by the second eccentric.

PRIOR ART Disclosure of the Invention

The present invention relates to a multi-piston pump as generically defined by the preamble to claim 1.

One such multi-piston pump is known for instance from German Patent Disclosure DE 101 53 834 A1. Such multi-piston pumps are used in motor vehicles, for instance, for building up the pressure in brake systems. The known multi-piston pump has two eccentrics, which are located in series and each drive three piston pumps. The piston pumps are disposed in two parallel planes at the level of the eccentrics. The piston pumps, each associated with an eccentric, are disposed at different angles to one another around the eccentric. To avoid pressure pulsations, two piston pumps of the first eccentric are connected to a piston pump of the second eccentric, and two piston pumps of the second eccentric are connected to a piston pump of the first eccentric. The eccentrics are disposed rotated by an angle of approximately 150° to one another. However, it has been proved in this respect that on the one hand the production effort and expense for such a multi-piston pump are quite high, since many low- and high-pressure lines have to be accommodated in the same housing. Moreover, the disposition of the piston pumps leads to non-uniform mechanical forces on a bearing of the motor and of the eccentric shaft. Moreover, the solution to this problem as proposed in this reference has the disadvantage that the hydraulic lengths of the bores of the first and second brake circuit differ, so that there are different pressure buildup times in the multi-piston pump.

ADVANTAGES OF THE INVENTION

The multi-piston pump according to the invention having the characteristics of claim 1 has the advantage over the prior art that it assures a uniform revolving load on a driveshaft and on the bearing that supports the driveshaft. As a result, noise can also be reduced, and in particular, pulsation-free pumping can be achieved. The multi-piston pump of the invention can furthermore be produced more simply and less expensively. This is attained according to the invention by providing that each piston pump of a first pump unit is disposed parallel to a piston pump of a second pump unit. It is thus assured that the piston pumps of the first and second pump units are disposed in the same way. This avoids the problem in which a different disposition of the piston pumps causes non-uniform mechanical forces to be exerted on the driveshaft and the bearings. The parallel disposition of the piston pumps of the first and second pump units furthermore makes for a reduced number of directions from which manufacture and assembly have to be done. In addition, the parallel disposition can also assure that line lengths of the lines from and to the first pump unit and of the lines from and to the second pump unit can be made equal. This has the major advantage that because of this, equal response times of different brake circuits that are supplied by the first and second pump units, respectively, can be achieved. Hence the brake circuits can be connected directly to a high-pressure switching valve in each brake circuit, without detours.

The dependent claims recite further advantageous features of the embodiment according to the invention.

Preferably, the first and second pump units include three piston pumps each. The piston pumps are preferably each disposed at an angle of 120° on the first and second eccentrics.

A further advantage is that the two brake circuits can now be embodied hydraulically symmetrically as well, which further facilitates production. Since the multi-piston pumps of the invention are preferably used in vehicles and are therefore mass-produced products, disposing the piston pumps parallel according to the invention results in potentially great cost reductions.

Also preferably, the first eccentric and the second eccentric are disposed rotated to one another at an angle. The angle is especially preferably approximately 150°.

To obtain an especially compact arrangement and to achieve the shortest possible line course in the housing of the multi-piston pump, the piston pumps of the first pump unit are disposed in a first half of the multi-piston pump, and the piston pumps of the second pump unit are disposed in a second half of the multi-piston pump.

The piston pumps of a pump unit are especially preferably disposed in one half in an angular range of approximately 120°. This makes for a very compact construction.

DRAWINGS

The invention is described in detail below in conjunction with the accompanying drawings. In the drawings:

FIG. 1 is a schematic, perspective elevation view of a multi-piston pump in one exemplary embodiment of the invention;

FIG. 2 is a schematic plan view which shows the disposition of the piston pumps of the first and second pump units; and

FIG. 3 is a schematic diagram of a brake system with the multi-piston pump according to the invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

A multi-piston pump 1 in an exemplary embodiment of the invention will be described below, referring to FIGS. 1 through 3.

The multi-piston pump 1 includes a housing 2, a first pump unit 3, and a second pump unit 4. The first pump unit 3 includes three piston pumps 3 a, 3 b, 3 c, and the second pump unit 4 includes three piston pumps 4 a, 4 b, 4 c. As can be seen particularly in FIG. 3, three piston pumps each are disposed around a first eccentric 5 and around a second eccentric 6. Two piston pumps 3 a, 3 b of the first pump unit 3 and one piston pump 4 c of the second pump unit 4 are associated with the first eccentric 5. One piston pump 3 c of the first pump unit 3 and two piston pumps 4 a, 4 b of the second pump unit 4 are associated with the second eccentric 6. The piston pumps 3 a, 3 b, 3 c of the first pump unit 3 finish the pressure in a first brake circuit I, and the piston pumps 4 a, 4 b, 4 c of the second pump unit 4 furnish the pressure for a second brake circuit II. Also shown schematically in FIG. 3 are a pedal P and a pressure fluid container D as well as four wheel brakes VR, HL, VL and HR. The brake circuit distribution in this exemplary embodiment is of the X type; the brake circuits I and II also, in a known manner, have inlet, outlet, switchover, and high-pressure switching valves, which will not be described in detail.

As can be seen from FIG. 1, the piston pumps 3 a, 3 b; 4 c are disposed in a first plane E1 in the housing 2, and the piston pumps 4 a, 4 b; 3 c are disposed in a second plane E2 in the housing 2. The first eccentric 5 is also disposed in the first plane E1, and the second eccentric 6 is disposed in the second plane E2.

Centrally in the middle of the housing 2, there is a recess 7 which serves to receive the first eccentric 5 and the second eccentric 6. A first low-pressure reservoir 8 a and a second low-pressure reservoir 8 b are also disposed in the housing 2. From the first low-pressure reservoir 8 a, low-pressure lines lead to the first pump unit 3, and from the second low-pressure reservoir 8 b, low-pressure lines lead to the second pump unit 4. As can be seen from FIG. 1, the low-pressure lines from the first low-pressure reservoir 8 a to the piston pumps 3 c and 3 b are quite short. The low-pressure line to the piston pump 3 a may also be realized relatively simply by means of two bores that are disposed at a 90° angle to one another. The high-pressure lines of the first and second pump units 3, 4 can be embodied equally simply. As shown in FIG. 1, between the piston pump 3 b and the piston pump 3 c of the first pump unit 3, which are disposed parallel to one another, only a short connection bore to a switchover valve or a master brake cylinder connection 9 of the brake circuit I is necessary. From each piston pump 3 a and 3 b, a respective horizontal/vertical high-pressure line then leads directly to the connection with the inlet valves in the brake circuit I. In the second pump unit 4, the high-pressure lines to a master brake cylinder connection of the brake circuit II are embodied equally simply. Between the two piston pumps 4 b and 4 c, once again only a short connecting line to the switchover valve is necessary, and from the piston pump 4 c, a bore leads directly to the connection with the inlet valves in the brake circuit II. The piston pump 4 a likewise communicates with the inlet valves in the brake circuit II via two bores disposed at a 90° angle from one another. As seen from FIG. 1, the connections 9, 10 are disposed on a step formed in the housing 2.

The same line lengths for the first and second pump units 3, 4 moreover assure that upon braking, no delay between the two brake circuits I and II occurs at the wheel brakes VR, HL and VL, HR, respectively.

The eccentric unit that includes the first and second eccentrics 5, 6 is disposed in the recess 7 and is driven by an electric motor, not shown. The electric motor can be mounted directly on the housing 2. The first eccentric 5 and the second eccentric 6 are disposed rotated by an angle of approximately 150° from one another (see FIG. 3); the selected eccentricity of the two eccentrics 5, 6 is the same. The parallel disposition of the piston pumps on the first and second eccentrics 5, 6 assures that during the operation of the multi-piston pump, uniform load changes are obtained, in a sequence of 0° . . . 30° . . . 120°, 150° . . . 240° . . . 270° during one motor revolution (360°), thus preventing irregular mechanical forces from acting on the bearings of the eccentric shaft in particular. As a result, especially low-vibration and especially uniform operation of the multi-piston pump can be attained, and noise production from hammering bearings or the like is precluded.

As can be seen from FIG. 2, the piston pumps 3 a, 3 b, 3 c of the first pump unit are disposed at an angular range α of 120°. In the same way, the piston pumps 4 a, 4 b, 4 c of the second pump unit 4 are disposed in an angular range β of 120°. The disposition of the piston pumps is such that the piston pumps 3 a, 3 b, 3 c of the first pump unit 3 are disposed in a first half 11, and the piston pumps 4 a, 4 b, 4 c of the second pump unit 4 are disposed in a second half 12. The piston pumps are represented schematically by lines in FIG. 2. The illustration in FIG. 2 again makes it clear that because of the disposition according to the invention of piston pumps in pairs and parallel on the first and second eccentrics 5, 6, an especially compact construction can be attained. The multi-piston pump 1 can be constructed symmetrically as a result, so that in particular hydraulic symmetry with regard to the line lengths in the housing can be achieved easily. It is possible as a result for the intake line connections of the multi-piston pumps to communicate directly with a high-pressure switching valve. FIG. 2 also makes it clear that the manufacture and assembly of the multi-piston pump can be markedly simplified as well, since for instance the piston pumps need to be installed, and bore need to be made, in the housing in only three directions. As a result, production and assembly aids can be simplified markedly. Moreover, the connecting lines between the individual piston pumps of each pump unit 3, 4 can be made especially short, since the piston pumps are provided in pairs and parallel. This also reduces any effort and expense for drilling in the housing 2 significantly. The inventive concept of the parallel disposition of piston pumps of different eccentrics in combination with the distribution of the piston pumps of one pump unit over two eccentrics 5, 6 can furthermore avert pressure pulsation during operation, and the symmetrical arrangement of the piston pumps on the eccentrics likewise prevents noise emission caused by mechanical load changes. The multi-piston pump of the invention is in addition especially economical and simple to produce. 

1-7. (canceled)
 8. In a multi-piston pump, including a housing, a first pump unit having a plurality of piston pumps for supplying pressure to a first pressure circuit, a second pump unit having a plurality of piston pumps for supplying pressure to a second pressure circuit, a drive mechanism and an eccentric unit having a first eccentric and a second eccentric, in which the first and second eccentrics each drive the plurality of piston pumps, and the first and second pump units each include at least one piston pump which is drivable by the first eccentric and one piston pump which is drivable by the second eccentric, the improvement wherein one piston pump each, driven by the first eccentric, is disposed parallel to a respective piston pump driven by the second eccentric.
 9. The multi-piston pump as defined by claim 8, wherein the first and second pump units each comprise three piston pumps.
 10. The multi-piston pump as defined by claim 9, wherein the three piston pumps associated with the first eccentric and the three piston pumps associated with the second eccentric are each disposed adjacent one another by an angle of 120°.
 11. The multi-piston pump as defined by claim 8, wherein the eccentrics are disposed at an angle to one another.
 12. The multi-piston pump as defined by claim 9, wherein the eccentrics are disposed at an angle to one another.
 13. The multi-piston pump as defined by claim 10, wherein the eccentrics are disposed at an angle to one another.
 14. The multi-piston pump as defined by claim 11, wherein the angle at which the eccentrics are disposed relative to one another is approximately 150°.
 15. The multi-piston pump as defined by claim 12, wherein the angle at which the eccentrics are disposed relative to one another is approximately 150°.
 16. The multi-piston pump as defined by claim 13, wherein the angle at which the eccentrics are disposed relative to one another is approximately 150°.
 17. The multi-piston pump as defined by claim 8, wherein the piston pumps of the first pump unit are disposed in a first half of the multi-piston pump, and the piston pumps of the second pump unit are disposed in a second half of the multi-piston pump.
 18. The multi-piston pump as defined by claim 9, wherein the piston pumps of the first pump unit are disposed in a first half of the multi-piston pump, and the piston pumps of the second pump unit are disposed in a second half of the multi-piston pump.
 19. The multi-piston pump as defined by claim 10, wherein the piston pumps of the first pump unit are disposed in a first half of the multi-piston pump, and the piston pumps of the second pump unit are disposed in a second half of the multi-piston pump.
 20. The multi-piston pump as defined by claim 11, wherein the piston pumps of the first pump unit are disposed in a first half of the multi-piston pump, and the piston pumps of the second pump unit are disposed in a second half of the multi-piston pump.
 21. The multi-piston pump as defined by claim 14, wherein the piston pumps of the first pump unit are disposed in a first half of the multi-piston pump, and the piston pumps of the second pump unit are disposed in a second half of the multi-piston pump.
 22. The multi-piston pump as defined by claim 15, wherein the piston pumps of the first pump unit are disposed in a first half of the multi-piston pump, and the piston pumps of the second pump unit are disposed in a second half of the multi-piston pump.
 23. The multi-piston pump as defined by claim 17, wherein the piston pumps of one pump unit are disposed in an angular range of approximately 120° in the first half and/or the second half.
 24. The multi-piston pump as defined by claim 18, wherein the piston pumps of one pump unit are disposed in an angular range of approximately 120° in the first half and/or the second half.
 25. The multi-piston pump as defined by claim 19, wherein the piston pumps of one pump unit are disposed in an angular range of approximately 120° in the first half and/or the second half.
 26. The multi-piston pump as defined by claim 20, wherein the piston pumps of one pump unit are disposed in an angular range of approximately 120° in the first half and/or the second half.
 27. The multi-piston pump as defined by claim 21, wherein the piston pumps of one pump unit are disposed in an angular range of approximately 120° in the first half and/or the second half. 